In 2014, a dedicated activity movement—Black Lives Matter—ignited an urgent national conversation about police killings of unarmed Black citizens. Online tools have been credited as critical in this effort, but researchers are only beginning to evaluate this claim.

A new research report—coauthored by Deen Freelon of American University, Charlton McIlwain of NYU Steinhardt, and Meredith D. Clark of the University of North Texas —examines the movement’s uses of online media in 2014 and 2015. To do so, the researchers analyze three types of data: 40.8 million tweets, over 100,000 web links, and 40 interviews of Black Lives Matter activists and allies.

Findings of the report include:

Although the #BlackLivesMatter hashtag was created in July 2013, it was rarely used through the summer of 2014 and did not come to signify a movement until the months after the Ferguson protests.

Social media posts by activists were essential in initially spreading Michael Brown’s story nationally.

Protesters and their supporters were generally able to circulate their own narratives without relying on mainstream news outlets.

There are six major communities that consistently discussed police brutality on Twitter in 2014 and 2015: Black Lives Matter, Anonymous/Bipartisan Report, Black Entertainers, Conservatives, Mainstream News, and Young Black Twitter.

The vast majority of the communities we observed supported justice for the victims and decisively denounced police brutality.

Evidence that activists succeeded in educating casual observers came in two main forms: expressions of awe and disbelief at the violent police reactions to the Ferguson protests, and conservative admissions of police brutality in the Eric Garner and Walter Scott cases.

The primary goals of social media use among the interviewees were education, amplification of marginalized voices, and structural police reform.

“One of the most striking and encouraging findings from our report is that through the duration of Black Lives Matter activity online, Black people have been driving the movement. Black voices resound and are amplified beyond all others, including mainstream media,” said Charlton McIlwain, associate professor of media, culture, and communication at NYU Steinhardt. “By dominating the conversation on social platforms like Twitter, and because of the digital environment that connects Twitter to the broader Web environment, Black Lives Matter has and continues to be poised for influence.”

In the report’s conclusion, the authors reflect on the practical implications of their findings.

“We hope this report contributes to the specific conversation about how Black Lives Matter and related movements have used online tools as well as to broader conversations about the general capacity of such tools to facilitate social and political change,” the authors wrote.